Since 2021, the City, with the support of its contractors, has been working to protect its tree canopy against the polyphagous shot-hole borer (PSHB) to minimise the potentially severe impact of the beetle on Subiaco’s renowned leafy, green streets.
The City is currently carrying out trial treatments on the Erythrina trees on Munsie and Willcock Avenues in Daglish to prevent spread of PSHB in this area.
Trial treatments are also being undertaken in Subiaco Common. Positive trees are treated with the insecticide Bifenthrin, which has had positive results in stopping the borer further infesting its host.
Proactive trials of preventative treatments to increase tree health and resistance to PSHB are ongoing across the City. This is currently addressed by applying Bioprime Trace (BT) and when trees are in noticeably poor condition, Glutathione (GT). BT is applied as a soil drench and when considered necessary a stem injection of GT is undertaken. This proactive approach aims to prevent further infestations as PSHB is known to infect trees in poor health.
On 18 June 2025, the National Management Group agreed that PSHB was no longer technically feasible to eradicate, and a decision was made to transition to management rather than eradication, with plans to continue to slow the spread of PSHB and minimise the risk of spread beyond the Perth metropolitan area.
Mayor David McMullen said, “For a local government that is home to some of Perth’s best green, leafy, suburbs, it will surprise no one to learn that the City of Subiaco is disappointed in the decision to abandon eradication in favour of the so-called ‘management’ phase of the State Government’s PSHB response.
“From a financial perspective, we are very concerned that the costs and impacts of ongoing PSHB management will be borne by our City, and private landowners. While limited funding is currently available for tree replacement, there is no funding being offered for ongoing management, treatment, and corrective actions. More funding is urgently needed. Otherwise, we will see a significant burden passed onto local governments, as well as private landholders – who will not all have the resources, expertise or the means to undertake sufficient corrective actions.
“The City of Subiaco will continue to liaise with other local governments and the Department of Primary Industries and Regional Development to discuss efficacy of trial treatments and to expand trial sites and methods.”
PSHB was first detected in the City of Subiaco in September 2022, and spread to further City locations in the months and years since.
There are a number of symptoms that indicate a tree may be infested. Visit our Trees and Verges webpage for more information on these symptoms and how to spot PSHB.
Residents who suspect they have borer damage to trees should call the DPIRD’s Pest and Disease Information Service on 9368 3080 or email padis@dpird.wa.gov.au. Further information can be found at www.agric.wa.gov.au/borer.
